Single-energy amplitudes for pion photoproduction in the first resonance region

We consider multipole amplitudes for low-energy pion photoproduction, constructed with minimal model dependence, at single energies. Comparisons with fits to the full resonance region are made. Explanations are suggested for the discrepancies and further experiments are motivated.Comment: 12 pages, 5 figure

Creation of a homogeneous plasma column by means of hohlraum radiation for ion-stopping measurements

In this work, we present the results of two-dimensional radiation-hydrodynamics simulations of a hohlraum target whose outgoing radiation is used to produce a homogeneously ionized carbon plasma for ion-beam stopping measurements. The cylindrical hohlraum with gold walls is heated by a frequency-doubled ($\lambda_l = 526.5$ $\mu m$) $1.4$ $ns$ long laser pulse with the total energy of $E_l = 180$ $J$. At the laser spot, the peak matter and radiation temperatures of, respectively, $T \approx 380$ $eV$ and $T_r \approx 120$ $eV$ are observed. X-rays from the hohlraum heat the attached carbon foam with a mean density of $\rho_C = 2$ $mg/cm^3$ to a temperature of $T \approx 25$ $eV$. The simulation shows that the carbon ionization degree ($Z \approx 3.75$) and its column density stay relatively stable (within variations of about $\pm7\%$) long enough to conduct the ion-stopping measurements. Also, it is found that a special attention should be paid to the shock wave, emerging from the X-ray heated copper support plate, which at later times may significantly distort the carbon column density traversed by the fast ions.Comment: 12 pages, 12 figure

Second-harmonic generation in the topological multifold semimetal RhSi

Recent experiments in the topological Weyl semimetal TaAs have observed record-breaking second-harmonic generation (SHG), a nonlinear optical response at 2? generated by an incoming light source at ?. However, whether SHG is enhanced in topological semimetals in general is a challenging open question because their band structure entangles the contributions arising from trivial bands and topological band crossings. In this work, we circumvent this problem by studying RhSi, a chiral topological semimetal with a simple band structure with topological multifold fermions close to the Fermi energy. We measure SHG in a wide frequency window, ? [0.27,1.5]eV and, using first-principles calculations, we establish that, due to their linear dispersion, the contribution of multifold fermions to SHG is subdominant as compared with other regions in the Brillouin zone. Our calculations suggest that parts of the bands where the dispersion is relatively flat contribute significantly to SHG. As a whole, our results suggest avenues to enhance SHG responses. © 2022 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Open access publication funded by the Max Planck Society

Magnetism and anomalous transport in the Weyl semimetal PrAlGe: Possible route to axial gauge fields

In magnetic Weyl semimetals, where magnetism breaks time-reversal symmetry, large magnetically sensitive anomalous transport responses are anticipated that could be useful for topological spintronics. The identification of new magnetic Weyl semimetals is therefore in high demand, particularly since in these systems Weyl node configurations may be easily modified using magnetic fields. Here we explore experimentally the magnetic semimetal PrAlGe, and unveil a direct correspondence between easy-axis Pr ferromagnetism and anomalous Hall and Nernst effects. With sizes of both the anomalous Hall conductivity and Nernst effect in good quantitative agreement with first principles calculations, we identify PrAlGe as a system where magnetic fields can connect directly to Weyl nodes via the Pr magnetization. Furthermore, we find the predominantly easy-axis ferromagnetic ground state co-exists with a low density of nanoscale textured magnetic domain walls. We describe how such nanoscale magnetic textures could serve as a local platform for tunable axial gauge fields of Weyl fermions.Comment: 42 pages, 5 figure

THE INFLUENCE OF HYDROGEN ALLOYING ON THE STRUCTURE, PHASE COMPOSITION AND TECHNOLOGICAL PLASTICITY OF THE TITANIUM ALLOY WITH ALUMINUM CONTENT EXCEEDING LIMIT SOLUBILITYABSTRACT

Установлено влияние водорода на структуру, фазовый состав и сопротивление горячей пластической деформации опытного сплава Ti–8,7Al–1,5Zr–2Mo, перспективного для изготовления силовых режущих хирургических инструментов. Установлено, что легирование водородом до 0,3 и 0,6 масс. % увеличивает объемную долю β-фазы при температурах α+α2+β-области и снижает предел текучести сплава на 115–200 МПа при температурах деформации 800–850С.The influence of hydrogen on the structure, phase composition and resistance of hot plastic deformation of the Ti–8.7Al–1.5Zr–2Moexperimental alloy, promising for the manufacture of power cutting surgical instruments, is established. It was found that doping with hydrogen to 0.3 and 0.6 wt. % increases the volume fraction of the β-phase at temperatures α+α2+β-region and reduces the yield strength of the alloy by 115–200 MPa at deformation temperatures of 800–850°C

Structure and Texture Formation behaviour in Two-Phase Titanium Alloys Billets Obtained by Additive Manufacturing

Работа выполнена с применением оборудования ресурсного центра коллективного пользования «Авиационно-космические материалы и технологии» МАИ.The effect of heat treatment on the structure, mechanical properties and texture of titanium alloy Ti–6Al–4V billets, obtained by additive manufacturing technology was investigated in this work.В рамках проведенного исследования было изучено влияние термической обработки на структуру, механические свойства и текстуру заготовок из титанового сплава ВТ6, полученных при помощи аддитивной технологии прямого лазерного нанесения материала